The expression \( \frac{B}{\mu_0} \) represents a quantity related to magnetic fields.
The dimensions of \( B \) (magnetic field) are [M T\(^{-2}\) A\(^{-1}\)], and the dimensions of permeability \( \mu_0 \) are [M L\(^{-1}\) T\(^{-2}\) A\(^{-2}\)].
Therefore, the dimensions of \( \frac{B}{\mu_0} \) are [M A L T\(^{-1}\)].
Let \( T_r \) be the \( r^{\text{th}} \) term of an A.P. If for some \( m \), \( T_m = \dfrac{1}{25} \), \( T_{25} = \dfrac{1}{20} \), and \( \displaystyle\sum_{r=1}^{25} T_r = 13 \), then \( 5m \displaystyle\sum_{r=m}^{2m} T_r \) is equal to:
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): The density of the copper ($^{64}Cu$) nucleus is greater than that of the carbon ($^{12}C$) nucleus.
Reason (R): The nucleus of mass number A has a radius proportional to $A^{1/3}$.
In the light of the above statements, choose the most appropriate answer from the options given below: